Guinsoo's Rageblade should probably cost a bit less, like they did IE/ER.
Guinsoo's Rageblade
Recurve Bow + Pickaxe + Blasting Wand + 675 = 3400
+30 (+50) Attack Damage +40 (+75) Ability Power +30% (+60%) Attack Speed
Unique: +15 On-Hit Magic Damage
Passive: Basic attacks grant +6% Attack Speed, +4 Attack Damage, and +7 Ability Power for 5 seconds, stacking up to 5 times. While at 5 stacks, gain Guinsoo's Rage, causing every other basic attack to trigger on-hit effects twice.
Made it 5 stacks and tweaked the numbers because round numbers are nicer. It's a compulsion.
I mostly made this thread out of curiosity for what Kog will build if the PBE BotRK changes go through.